Renal autotransplantation in sheep--preparation and physiology

A novel procedure for renal autotransplantation in sheep is described. The operative procedure involved two preliminary operations for preparation of carotid artery and jugular vein loops and of a Wright-type parotid fistula. At transplantation the renal artery and vein were anastomosed end-to-end to carotid artery and jugular vein and the ureter was anastomosed end-to-end to the parotid duct. The cranial ends of the carotid artery, jugular vein and parotid duct were ligated and the parotid gland was denervated. The remaining abdominal kidney was removed 2 days after transplantation. Over periods now as long as 36 months, glomerular filtration rate was 24.1 +/- 0.7 ml/min and effective renal plasma flow was 204 +/- 6 ml/min (73 determinations in 7 sheep), compared to values of 48 +/- 4 and 305 +/- 26 ml/min previously reported for sheep with both kidneys in situ. The physiological response of the kidneys to water load and deprivation, arginine-vasopressin injection, intravenous hypertonic sodium load and 24 h sodium depletion have been examined and show the transplanted kidneys responded in the appropriate manner. Maximum urine osmolality of up to 1000 mOsmol/kg was observed after 24 h water deprivation, and minimum osmolality of 108 +/- 25 mOsmol/kg was observed after administration of 75 ml/kg oral water load. Fractional sodium reabsorption was greater than 99.9% after 24 h sodium depletion, whilst it fell to 92.5 +/- 0.5% after intravenous administration of a hypertonic NaCl load. All these values are in the same range as observed for normal sheep following similar treatment. This preparation provides a sole kidney with immediate access to its blood vessels and secretions for physiological and pharmacological research.